M4OSA_Random.c revision 855ec7c4be7ad642721909d5837a8d25a117c22f 
1/*
2 * Copyright (C) 2004-2011 NXP Software
3 * Copyright (C) 2011 The Android Open Source Project
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17/**
18 ************************************************************************
19 * @file        M4PSW_Trace.c
20 * @brief        Trace function for trace macros
21 * @note        This file gives the implementation of the trace function used
22 *                in the trace instrumentation macros
23 ************************************************************************
24*/
25
26#include <stdio.h>  /*for printf */
27#include <stdarg.h> /* ANSI C macros and defs for variable args */
28#include <stdlib.h>
29#include <string.h>
30#include <time.h>
31
32#include "M4OSA_Types.h"
33#include "M4OSA_Error.h"
34#include "M4OSA_Memory.h"
35#include "M4OSA_Mutex.h"
36/**
37 ************************************************************************
38 * @fn         M4OSA_ERR M4OSA_randInit()
39 * @brief      this function initialize the number generator
40 *               this function must be called once before any call to M4OSA_rand()
41 *               need the stdlib and time libraries
42 * @note
43 * @param
44 * @return     M4NO_ERROR
45 ************************************************************************
46*/
47
48M4OSA_ERR M4OSA_randInit()
49{
50    int i;
51
52    srand(time(NULL));
53
54    /* Windows' rand is rotten, the first generated value after the init
55    above is not random enough, so let's shake things a little... */
56
57    for (i=0; i<100; i++) rand();
58
59    return M4NO_ERROR;
60}
61/**
62 ************************************************************************
63 * @fn           M4OSA_ERR M4OSA_rand(M4OSA_Int32* out_value, M4OSA_UInt32 max_value)
64 * @brief       This function gives a random number between 1 and max_value
65 *               (inclusive) with approximately equal probability, and
66 *               returns this number in out_value. For instance, a max_value
67 *             of 6 will simulate a fair 6-sided dice roll.
68 * @note
69 * @param      out_value (OUT): on return, points to random result
70 * @param       max_value (IN): max expected value
71 * @return     M4NO_ERROR
72 ************************************************************************
73*/
74
75M4OSA_ERR M4OSA_rand(M4OSA_Int32* out_value, M4OSA_UInt32 max_value)
76{
77    if( (out_value == M4OSA_NULL) || (max_value < 1) )
78    {
79        return M4ERR_PARAMETER;
80    }
81
82    (*out_value) = rand();
83    /* notice this algorithm will only work for max_values such that the multiplication
84    won't overflow, which means that max_value typically shouldn't go over the range of
85    an Int16. */
86    (*out_value) = (((*out_value) * max_value) / ((M4OSA_UInt32)RAND_MAX + 1)) + 1;
87
88    return M4NO_ERROR;
89}
90
91
92